This invention relates to vehicles which are specially designed for use in underground coal mines and, more particularly, to a joint for connecting two mine car vehicles which allows them to move laterally and vertically relative to each other.
It is known to connect a two-wheeled tractor portion of a mine shuttle car with a trailer which has two or more wheels through a pivot connection so that hydraulically operated cylinders can be used to turn one relative to the other for maneuvering them around sharp corners. In these mine vehicles, however, there is no provision for tilting the trailer to facilitate loading.
In one embodiment of such an arrangement where a tractor and trailer are use to move roof supports from one location in a mine to another, it is extremely burdensome to load a roof support onto a trailer where the rear-end portion of the trailer is raised above the ground.
In another form of mine vehicle where a load carrying frame or bucket is connected to the tractor, the bucket is normally raised and lowered to scoop up coal or other materials through a hydraulic mechanism. The load carrying capacity of known devices of this type is limited because the bucket is not self-supporting, but must be carried by the tractor.